1. Field of the Invention
The present invention relates generally to a transition device for an optical network enclosure allowing for the transition of an optical fiber contained within an optical fiber cable into a furcation tube thereby providing strain relief, protection of the optical fiber, and a means for attaching a field-installable optical connector.
2. Technical Background
Optical fibers are widely used in a variety of applications, including the telecommunications industry which utilizes optical fibers in a number of telephone and data transmission applications. The extremely wide bandwidth and low noise operation provided by optical fibers naturally leads to a broad range of possible uses, and the variety of applications in which optical fibers are utilized continues to grow. For example, optical fibers no longer serve as merely a medium for long distance signal transmission, but are being increasingly routed directly to the home and, in some instances, directly to a an office desk or other work location.
Outdoor fiber installations require robust fiber protection and therefore significant physical jacketing and reinforcement of the glass fiber is frequently utilized. The typical outdoor optical fiber cable typically includes one or more coated optical fibers disposed within a buffer tube surrounded by a protective jacket. Additionally, strength members may also be utilized to provide tensile strength and structural rigidity along the length of the cable. The strength members may be attached to, or otherwise enclosed within the outer protective jacket. The combination of the jacket, strength members, and buffer provide a rugged and durable optical fiber cable for outdoor installation. However, when the optical fiber cable reaches the customer's premises, it is necessary to strip the protective jacket, strength members, and buffer so as to allow the optical fiber to be connected to another optical fiber or optical device within a network enclosure. Generally, a furcation tube may be used to provide a more manageable jacket for the optical fiber. A furcation tube is a thin walled tube with an internal diameter greater than that of the coated optical fiber and an outer diameter sized to permit the installation of a connector onto the furcated optical fiber. The installation of the furcation tube provides a field optical fiber that can be easily installed, for example, on a field installable connector and subsequently optically connected to another optical fiber or optical device within an optical network enclosure, such as a network interface device.
In an optical network, it is necessary to split, couple, and provide transitions between individual branches of the optical network and also to provide transitioning from the optical network to a customer's equipment. A number of different types of network enclosures are used to house the optical fiber and associated connectors needed to connect customers to the optical network. Examples of enclosures include aerial mounted fiber optic closures, ground-level pedestals and cabinets, and below grade closures. Regardless of the enclosure and installation type, one of the primary purposes of the enclosure is to provide environmental protection and/or security to one or more fiber optic transitions in an optical network. Generally, this involves the use of connectors to establish quality, reliable connections between adjoining optical fibers. However, in order to install the optical connectors, the protective jacket of the optical fiber cable must be removed and the optical fiber contained within the optical fiber cable must be exposed.
An efficient method of installing optical fiber in a field installation is to use mechanical splice connectors. Mechanical splice connectors mount upon the end of an optical fiber and provide a means for easily and reliably connecting adjoining optical fibers. Such mechanical splice connectors are well known in the art, but generally require “up-jacketing” an optical fiber to include a loose-tube buffer, typically around 900 microns in diameter. One simple way to accomplish this is by applying a furcation tube onto the optical fiber. The installation of a furcation tube requires the removal of the protective jacket of an optical fiber cable leaving exposed the portion of the optical fiber between the end of the jacketed optical fiber cable and the beginning of the furcation tube to the environment. Exposing the optical fiber to the outside environment introduces serious risks of damaging the optical fiber and introducing microbends in the optical fiber that may significantly degrade the quality of optical transmission. Therefore, it would be advantageous to provide a protective body, referred to herein as a furcation body, that would permit transitioning the optical fiber contained within an optical fiber cable into a furcation tube that may further provide means for attaching a fiber optic connector, such as a mechanical splice connector.
In view of the aforementioned shortcomings, improved apparatus and methods are needed for transitioning a field optical fiber contained within an optical fiber cable into an optical network enclosure for connection to another optical fiber or device.